Oh, my yes have had experience with mrsa but not with a child however I will tell you our story and try to help you with your fears. Listen I'd call your child's doctor and have them step up the beat on the lab from which the urgent care care gets reports from...you need to know asap if it's mrsa and frankly they should be able to tell you within 24 hours or less. Your child's doctor can get people jumping plus they need to know about this.
She also should be looked at if you have no results in 3-4 days by her doctor not the urgent care. So I'd call them now and set up an appt for you ped to see her asap.
Mrsa you can't get it unless it's uncovered. There are people known as carriers so that's why it's now out in the world everywhere not just in hospitals. People they found children can carry it in their nose so that's another reason why when a kid does a sneeze it's important wo wash hands or use a santizer when blowing your nose, adults can be carriers too.
Now don't worry an antibiotic can work but in not working sometimes they have to do a bit of surgery to remove the dead tissue of infection. My husband got mrsa had a few surgeries in a week with it that's why i say call your doctor and have them get on the lab and/or the urgent care, you need to know incase she needs surgery. Don't mean to scare you but it's a real fact and can be a serious illness. Yes it's scary and it can be a horror story so yours isn't kick some tail and get people moving. My husband just had to be tested again when he had surgery for something else they tested under his arm and told me 24 hours for results hospital policy once you've had mrsa and surgery at the same hospital even if it's for something else.
Sorry i can't ease your mind since it's serious but don't worry since she may not even have it and be a pain in their behinds about getting the results plus seeing her doctor about it or a specialist asps!
Thoughts and prayers are with you
PS DON'T SOAK THIS INFECTION IF IT'S MRSA SOAKING WILL MAKE IT WORSE AND YES IN ESPON SALT NO ESPON SALT WE DID THAT AND THE DOCTOR SAID IT MADE IT WORSE! DON'T DO HOME REMEDIES WITH THIS WOUND PLEASE!
One last thing it's not a problem when it affects organs it's a problem period if it effects organs it's bad.....you can still need surgery even if it's not effecting an organ....think dead tissues not responding to antibotic.